Luminair



LUMINAIR Filed July 20, 1929 INVENTOR 501 MM [in we:

ATTORNEY Patented Apr. 7, 1931 2 UNITED STATES PATENT OFFECE SOLOMONENGLISH, OF LONDON, ENGLAND, ASSIGNOR TO HOLOPHANE COMPANY, INC. OF NEW YORK, N. Y., A CORPORATION OF DELAWARE LU INAIR 7 Application filed July 20, 1929, Serial No. 379,709, and in Great Britain July 31, 1928.

The invention relates to those luminairs whichcomprise a reflecting shade of prismatic glassware for use with a fairly localized light source for example an incandescent 1 electric lamp. y l y j- Hitherto such reflectors have been made with a'smooth inner surface and 90 prisms, usually radially arranged on the external surface, in whichtherays are twice totally 10 reflected. I

"Briefly stated the present invention consists in the useof a smooth outer surface in conjunction with internal prisms in which the'raysundergo only 'asingle total reflection. This has three importantadvantages. In thefirst place, the exterior being smooth, is easy to clean. In the second place since there is only one reflection there is less internal loss of light. In the third place,'particularly when used with an ordinaryxgas filled electric lamp, the proportion 'of light actually reflected in the desired direction is much higher than with the externalprisms and the reflector is thereforegmoreelficient. In a shade having its exterior and interior surfaces "in the form of surfaces of revolution, the prisms then have one face substan-' tially parallel with the axis of the shade and the other face substantially parallel with the direction of light incident on the shade at their particular locations so that practically all the light is incident on the vertical faces. The outer surface ofthe shade, which forms the third side of the prismsis arranged at such an'angle as to produce the internal'reflection, in the desired direction, while forming a smooth continuous surface. Advantageously the vertical height of all the prisms is the same. In practice this leads to a shape of diverging form very similar to that of the shades hitherto in use. Moreover the structure is one which can be moulded without difficulty. c

With apractical construction of a shade for use with its axis vertical, itis preferable that the prism construction, above explained, should not becarriedfmore than about 10 abov'ethe horizontal planepassing through the light source. Above this level it is there fore preferable to provide a further reflector,

by interposing a filter of daylight blue glass between the mouth of the shade and the stantially along their original paths. In

that case, this part of the reflector may be spherical about the'nominal light center, or, 50 in the case of a gas filled lamp, if more precise control of the light is required, the prism bearingsvsurface may be a surface revolution generated about the axis of the shade by a circular arc struck as closely as possible about the actual'position of the filament which itself follows a circle aboutthe axis of the shade, a v

The shade above described reflects-such a v large portion of light and allows so little to escape by transmission that it may be used very satisfactorily for spot or flood lighting, it then being designed to give a parallel beamj For some purposes the open mouth oft-he shade is preferably closed in by a glass cover plate which may makea dust tight joint with the shade in known manner by means of flat surfaces and metal clips. This completes a closed device with a smooth exterior on the greater part. When the shade islused for general illumination it may be desirable to 'difiuse the light and for this purposethe cover plate may have internal corrugation arranged in any desired manner but preferably circumferentially/ In addition the exterior of the cover plate may have further diffusing flutings arranged in any desired manner but preferably radially. The inte- .rior of the shade and cover when desired may also be lightly satin finished.

The closed unit above described can with great advantage be used as daylight unit cover plate. A high degree of efliciency is obtained since practically all the. light passes through the filter and cover, While the diffusing flutes render the filter completely invisill) ible when the unit is out of use and practically invisible when in use. i

The accompanying drawings show, for purposes of illustrating the present invention, one of the many possible embodiments in which the invention may take form, it being understood that the drawings are illustrative of the invention rather than limiting the same.

In the drawings:

Figure 1 is a side elevational view with parts in section showing a luminair employing the shade, bottom cover plate, and daylight plate; and

Figure 2 is a top plan view, on part of which shows the outside of the shade, while the other part shows the inside of the bottom cover plate.

As shown in Figures 1 and 2, the shade which is in one piece, comprises a portion 1 with a smooth exterior which extends to about 10 or so above the nominal center 2 of the light source, and a spherical portion 3 having its center at 2 and having radial 90 reflecting prisms 4 of the well known kind on its exterior. At its upper end the shade is provided with a rim 5 by which it is held when in use.

The portion 1 has circumferential prisms 6 moulded on its interior, the faces 7 of the prisms being vertical. The faces 8 of the prisms are substantially parallel with the direction of rays from the light source 2 and for convenience in manufacture they are divided into groups, all the prism faces 8 in any one group having the same angle. Thus commencing fro-m the top, the first four faces 8 are inclined upwards at 4 to the horizontal, the next three are horizontal, the next three are inclined downwards at 4 to the horizontal, the next four at 8, the next five at 12, the next five at 16 and the last four at 20. All the prisms are of the same total vertical height.

At the lower edge the shade is provided with a beaded rim 9 which forms a step and flat surface to make a dust proof joint with the rim 10 of a cover plate 11, the two parts being held together in use by metal clips 11a lodging in recesses 11?) in tthe cover plate and over the rim 9. The rim 9 may have vertical flutes 12, which are omitted where the metal clips pass over it.

The cover plate 11 may have similar vertical flutes at 14- and its exterior is provided with radial flutes 15 while its interior is provided with circumferential prisms 16 towards the outer part and circumferential flutes 17 towards the inner part. At the center is a small hollow tip 18 with vertical flutes 19 formed inside.

lVhere one desires to control the color of the emitted light. a color screen such as a daylight blue glass plate 20 may be placed 65 inside the unit above the cover plate.

It is obvious that the invention may be embodied in many forms and constructions within the scope of the claims, and I wish it to be understood that the particular form shown is but one ofthe many forms. Various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

hat is claimed is:

1. A reflecting glass shade having its ex- 7 terior and interior surfaces in the form of surfaces of revolution, the interior surface being formed of prisms having one face substantially parallel with the axis of the shade and the other face substantially parallel with the direction of light incident on the shade at their particular locations, theshade having an additional reflector, extending beyond the useful range of prisms at the .end remote from the open end of the appliance.

2. A reflecting glass shade having its exterior and interior surfaces in the form of surfaces of revolution, the interior surface being formed of prisms having one face substantially parallel with the axis of the shade and the other face substantially parallel with the direction of light incident on the shade at their particular locations, the shade having an additional reflector, extending be.- yond the useful range of prisms at the end remote from the open end .of the appliance, the additional reflector being shaped to redirect the rays approximately through the light source.

8. A reflecting glass shade having its ,ex- '100 terior and interior surfaces in the form of surfaces of revolution, the interior surface being formed of prisms having one face substantially parallel with the axis of the shade and the other face substantially parallel with the direction of light incident on the shade at their particular locations, the shade having .an additional reflector, extending beyond the useful range of prisms at the end remote from the open end of the appliance, the additional reflector being shaped to redirect the rays approximately through the light source and having radial 90 prisms on its exterior.

4:. A luminair comprising a light source, a glass shade about the light source, the shade having a smooth outer surface, the inner surface being made up of circumferentially disposed prisms each having a surface to receive light from the light source to direct the light onto the outer surface where it is totally reflected and directed out through the other surface of the prism, and a reflector above the prisms adapted to return the upwardly directed light.

5. A luminair comprising a light source, and a refractor about the light source, the refractor having a smooth exterior and being downwardly and outwardly flaring to intercept a zone of light above and below the 130 light source and comprising a series of single reflection catadioptic prisms to redirect the light in an axial beam, the refractor being further provided with externally disposed prisms above the catadioptic prisms adapted to reflect light back toward the light source; 6. In a luminair, the combination with a light source of a one piece conical refractorhaving a smooth outer surface and a series of circumferentially arranged interiorly disposed prisms adapted, in conjunction with the outer surface of the refraotor, to act on light rays from the light source and redirect them into a beam parallel with the axis of the refractor, the refractor also having a spherical portion above the conical portion provided with external reflecting prisms to return light toward the light source.

Signed at 8, St. Martins Place; London, England, this 5th day of July, 1929.

' SOLOMON ENGLISH. 

